Open Brain Coral Care Guide for Beginner Reefers

This open brain coral care guide is created for beginner reefers. Probably you’ve just bought open brain coral, or maybe you consider keeping one? This article is the only source you’re gonna need to keep the coral. Here is brief info:

Basic Information

Scientific name: Trachyphyllia spp.Common name: Open Brain CoralType of Coral: Hard (LPS)
Average size: Up to 8 inches in diameterOptimal Spacing: 2 to 3 inchesСomplexity: Perfect for beginners

Next on the agenda: common problems and solutions related to open brain coral, water quality, alkalinity, lighting, fragging. Continue reading the article to get the most relevant information about this beautiful coral (you can easily skim to the part you need).

Natural habitat and appearance

Open brain coral is classified as LPS (large polyp stony). They are free-living coral, meaning that their colonies are able to inflate the tissue and move around with an aid of water current. It’s a great feature of these corals: if the surrounding conditions are unpleasant in any way, open brain coral can simply change the location. Although when it comes down to the aquarium setting, movement can be limited. Because even the most cutting-edge pumps and water flow systems can’t be compared with the ocean. So, your coral won’t organize “The Shawshank Redemption” while you sleep. 

Hint: If you want to know more about LPS corals, make sure to read this article.

It is a small coral that rarely exceeds the size of an average iPad (about 8 inches). Of course, large specimens are also found, but this is more of an exception to the rule. Open brain corals are normally a single, large polyp that populates the Indo-Pacific. On occasion, you do find colonies that consist of one larger colony and then what appears to be a daughter colony right next to it. Sometimes it looks like corals may be budding (asexual reproduction method) but that is not the case. What’s actually happening is during the coral spawning event you’ll get a stray spawn. 

When open brain coral grows up, it looks like a double or triple-headed trachea. The most beautiful species are commonly found around the east coast of Australia and Indonesia. Those species around Indonesia may lack that impressive size of the “Australia” type but Indonesian open brains have the same striking colors. 

Open brain corals are one of the most desired species both for beginners and pros. Majorly due to diverse coloration and the intensity of those colors. Starting from those monochromatic green striped colonies to rainbow-like show-stopping colonies. Including yellows, reds, orange-like, and even pink. 

Placement in a Reef Tank

Open brain coral feels great at the bottom part of the aquarium. Consider placing the coral in a dimmed part of the tank. Don’t forget about water flow and compatibility. You can read about those further in the article. But for now, place your open brain coral at least 3 inches away from other species to prevent accidents. 

Water Quality

Provide your open brain coral with high-quality water and you’ll resolve 80% of problems. What do I mean by high quality? Water quality boils down to a few basic aspects. Which are calcium, alkalinity, temperature, flow, and pH. 

Let’s discover in detail:


Being a major ion in saltwater, calcium affects water quality a lot. In the oceans, its level hovers around 400 to 450 ppm. You should use the same range for open brain coral. I recommend you use 400ppm value as a starter. Then you may adjust that based on your observation. If coral feels lame, you may want to level up the value up to 450 ppm. Make sure to adjust calcium step-by-step though. Adding 5 or 10 ppm weekly is optimal.

Useful tip: Mature and older corals demand a little less calcium. Younger corals require more calcium to complete the skeleton formation process. 


Stick to medium alkalinity of 450 to 550 ppm. 500ppm is the optimal value for open brain corals. Keeping medium alkalinity is perfect for beginners. As it excludes any chance of problems with corals. Even though this number may not be 100% perfect, it guarantees your coral feels great and not suffering. You can experiment in the future, once your corals are healthy and adapted. 500 ppm is a great muster point in this regard.

Tip: use this calculator to convert ppm to meq\L (another popular way to measure alkalinity)

pH (power of hydrogen)

If there’s only one synonym for “balance”, that would be pH. In the context of reef-keeping pH is the highest law of the universe. Screw up with pH once and your whole aquarium suffers to death…As dramatic as this may sound, it is the truth. You may want to freeze values of pH around 8.1 to 8.4 for open brain coral.

Ok, but what should you do, if pH is out of desired range? 

Well, If pH in your aquarium is disturbed, arrange a partial water change immediately. Remember that adding baking soda raises pH, while vinegar and lemon juice lowers it down. You may consider “pH down” products to regulate the pH. Never get products containing muriatic or sulfuric acids inside the pack.

Temperature and Flow

Open brain coral appreciates low to medium water flow. There are two reasons to put low to medium water turbidity.

  1. Water remains clean. Low circulation can lead to the accumulation of detritus buildups (dead material). This can cause coral stress or even death. Providing some elevated water flow around the coral can prevent the accumulation. Even medium flow helps in cleaning, as corals have self-cleansing mechanisms. It’s hard to overdo water flow, but you can notice that by paying attention to the appearance of the coral. If you are giving too much flow, one of the coral’s sides will look like getting slammed. 
  2. Low or even zero water flow makes it much easier to feed the coral. As you want to give your open brain coral every opportunity to digest the food. Note that this applies only to targeted feeding.

The perfect temperature is 72 to 78 degrees Fahrenheit. These numbers are true for almost every coral found in Indo-Pacific. The reason is simple — you put corals under natural, wild-like conditions. Meaning medium flow, and warm water. Overdo one of those, and your coral will suffer to death because of unnatural parameters.


While some corals are more light-loving compared to others, open brain coral tend to be less demanding in this regard. In fact, they probably feel better in less intense lighting conditions. Low to medium lighting is a perfect way to keep them fresh, young, and healthy. I already knew that before writing this article but wasn’t sure about numbers. So, I’ve asked my biologist friend, made some research on forums, and talked to specialists at a local store. Here is what I’ve discovered about lighting intensity:

Biologist friend 60 to 110 PAR
Reef forums (opinion of reef-keepers)50 to 150 PAR
Quora 70 to 90 PAR
Store specialists40 to 60 PAR

Summing up, the perfect range for your open brain coral lies within 50 to 100 PAR. If your tank is in a higher light, it’ll take some time for this coral to adjust to its new surroundings. Bear in mind that excessive lighting can burn any coral. Sift through to find detailed solutions in the Biggest Problems section of this article.

Tip: if you doubt about lighting, simply lower intensity until it’s clear that coral feels safe & sound. Once your coral is stable, you can ramp up the intensity (for other species) 

As for spectrum (a.k.a as “quality” of lighting), it’s a less flexible pick. The majority of corals love a range from 400 to 470nm. Stick more to the blue part of the spectrum as opposed to white. 

I prefer the 60\40 rule. Meaning that 60% of the time I use the blue spectrum (40% left is for the white spectrum). In practice, I expose corals for 10 hours with 60% blue and 6 hours with 40% white. Followed by an 8-hour pause. And by a pause, I mean complete darkness. Not even moonlight shouldn’t “touch” the coral. Spectrum is as important as intensity (PAR). Remember that the wrong spectrum can cause necrosis or coral’s instant death.

Compatibility with Other Species

Open brain corals are great companions for almost every marine animal. Make sure to fill your tank with reef-safe fish only to avoid problems in the future (especially if you are a beginner). A vivid example of reef-safe kind of fish could be goby, clownfish, angelfish, tang, mandarinfish, dragonettes, and etc.

As for other corals, here is a short table of relationships among different types of corals.

AggressiveNot compatibleNot compatibleMaybe
DefensiveNot compatibleCompatibleCompatible

Any coral is classified as one of the three: aggressive, defensive, or passive. Aggressive corals may invade territory, burn & sting neighbors (both fish and corals). Defensive species act in a more peaceful way, acting only when some kind of danger appears. Passives do nothing, they are the most peaceful type. This classification is created only for simplicity, there are no strict borders, stating that X coral is aggressive 100% of the time, while Y is passive. 

Open brain coral is generally classified as moderate aggressive coral. Something between defensive and aggressive. If you put the coral very close to other species, it may end badly… As open brain corals may sting neighbors with tentacles. Keep a solid distance of at least 3 to 5 inches to protect your corals. 

The Biggest Problems Related to Open Brain Coral 

Let’s start from the greatest and most common problem:


Bleaching is also known as discoloration. To put it simply — your coral is about to fade in color. This happens because of special algae which feed the coral. Under stress conditions, any coral expels the algae and switches to “economy” mode. When that happens, all unnecessary stuff suffers (like coloration)

The algae are very subtle in nature and have zero tolerance to external discomfort. Meaning that any stress (light, temperature, nutrients, etc) can cause the algae to leave the coral. To avoid that, track your water quality as frequently as possible. Check pH, temperature, water flow, and visually evaluate how clean the tank is. Some corals like “a little bit dirty” water. Don’t overuse carbon and other cleansing tools.

The most efficient way to save corals from bleaching is a partial water change. Consider doing this procedure once or twice a week.

Not opening 

Open brain coral may not open up immediately upon arriving at a new aquarium. Give the coral some time. Usually, this period shouldn’t be more than 3 days. If nothing changes, replace your coral. If this also didn’t help change lighting, water parameters, etc. Consider a partial water change as well. Most of the time, water quality is the key.

Tip: leverage water changes to keep your tank clean and pH-balanced.


This is the last thing you want to encounter. Infection occurs when microorganisms inhabit your tank. Such as bad algae, bacterias, etc. To get rid of those, make sure to maintain your filtration system regularly, and dip any coral before placing it into the tank. 

Short isolation of any new coral can save a lot of time in the future. Get a dipping product and immerse any coral for 5 to 10 minutes. This way your aquarium will be out of danger.

Feeding Open Brain Coral

Open brain corals are photosynthetic. Meaning that they get nutrients from the products of the sun’s light. The whole process is carried out by special algae called zooxanthellae. It lives inside the coral’s flesh. Zooxanthellae absorb light and produce simple sugars that the coral can consume for energy. 

In addition to photosynthesis, these corals are adept feeders. Open brain corals can grab & consume a wide variety of foods. Ranging from coral formulated sinking pellets to deep-frozen food. Normally, these corals are pillow-like fluffy tissue but that changes as they sense the presence of any food in the water. As soon as open brain coral detects the faintest hint of food, its feeding regimen is activated. Turning it into a beast covered with tentacles. Although this coral can consume a lot of food, you still can overfeed it. Which is really bad… The risk of overfeeding is water pollution (which is pretty hard to remedy)

I don’t recommend targeted feeding for open brain coral. It can consume a major part of energy via photosynthesis and absorb some directly from the water. 

Tip: use a protein skimmer and powerful filtration system to cure overfeeding side-effects. Even though filtration is a great tool, it doesn’t give 100% protection from bacterias.

Open Brain Coral & Fragging

You should bear in mind that open brain corals may be very subtle sometimes. Use sharp and clean tools to treat the flesh of the coral. Plus, these corals are slow-growers. It takes much more time for the species to grow compared to other corals.

The main thing before anything else is to make sure your open brain coral has two (or more) mouths on it. If the coral has less than two mouths, the fragging time hasn’t come yet…

Before you start, make sure to prepare protective equipment. Those would be latex gloves and goggles. While gloves will protect your hands from toxins released, goggles make sure your eyes are safe as well.

As for me, the best tool to frag open brain coral is a saw or bone shears. However, any other tools are just fine. It’s more about taste… The only thing required is technique. Once you’ve mastered the tool, it would fit the coral. I prefer bandsaw because it allows the cut to be very subtle and clean. Which makes glue spreading much more convenient. Some people don’t recommend bandsaws, they insist on a band method instead. The reason for that is saw-cutting may damage the coral and its shape dramatically. Once an open brain coral is cut, it may take a couple of years until it’s fully recovered. But the shape would never be the same if you did anything wrong. In this regard, a band method is safer. 

I hope this article was relevant and useful for you. You can also find another helpful article about green star coral here. Make sure to read it, as green star coral is a great alternative to open brain coral. If you didn’t decide about specific coral, that article may change your mind.

Bart Sprenkels

I have been keeping multiple aquariums since I was 18 years old. Just like many of you, I started with two goldfish but quickly learned they were not suitable for aquariums. Later, I switched to a tropical community tank and I also have two pet musk-turtles in a bigger aquarium. You can read more about me here.

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